Conventional practices for the removal and recovery of components during drying of coated materials generally utilize drying units or ovens. Collection hoods or ports are utilized in both closed and open drying systems to collect the solvent vapors emitted from the substrate or material. Conventional open vapor collection systems generally utilize air handling systems that are incapable of selectively drawing primarily the desired gas phase components without drawing significant flow from the ambient atmosphere. Closed vapor collection systems typically introduce an inert gas circulation system to assist in purging the enclosed volume. In either system, the introduction of ambient air or inert gas dilutes the concentration of the gas phase components. Thus the subsequent separation of vapors from the diluted vapor stream can be difficult and inefficient.
Additionally, the thermodynamics associated with the conventional vapor collection systems often permit undesirable condensation of the vapor at or near the substrate or material. The condensate can then fall onto the substrate or material and adversely affect either the appearance or functional aspects of the material. In industrial settings, the ambient conditions surrounding the process and processing equipment may include extraneous matter. In large volume drying units, the extraneous matter may be drawn into the collection system by the large volumetric flows of the conventional drying systems.
It would be desirable to collect gas phase components without substantially diluting the gas phase components with ambient air or inert gases. Additionally, it would be an advantage to collect gas phase components at relatively low volumetric flows in an industrial setting in order to prevent the entrainment of extraneous matter.